Method for producing wood flour



PATENT OFFICE.

JOHN J.CUNNINGHAM, OF GLENS FALLS, NEW YORK.

METHOD FOR PRODUCING WOOD FLOUR No Drawing.

To all whom it may concern:

Be it known that 1, JOHN J. CUNNING- HAM, a citizen of the UnitedStates, and a resident of Glens Falls, in the county of Warren and Stateof New York, have invented a new and Improved Method for Producing WoodFlour, of which the following is a full, clear, and exact descriptlon.

The invention relates to wood flour such as is used in the manufactureof phonograph records and other articles.

The object of the invention is to provide a new and improved method forproducing wood flour from raw sawdust in an exceedingly economicalmanner.

The method consists essentially in screening raw sawdust, grinding thescreened sawdust under development of heat to vaporize the moisturecontained in the raw sawdust, separatin the vapors and the reducedsawdust, and bolting the sawdust to separate the coarse sawdust from thewood flour.

In order to carry this method into effect, I proceed in detail asfollows: The raw sawdust as received from a saw mill, pulp mill or otherplant and forming practically a valueless by-product, is passed overscreens of a proper mesh to screen the sawdust from chips, pieces ofbark and similar larger pieces. The screened raw sawdust is next passedin close proximity to a large magnet for the purpose of attractingmetallic ob jects such as nails,'points of saw teeth and the like, tocompletely free the screened sawdust of the metal pieces. The screenedraw sawdust is next reduced by grinding it in a grinding mill of theflour mill type, having a fixed and a rotating stone provided on theiropposite faces with the usual grooves or channels. By subjecting the rawsawdust to the grinding action between the mill stones suflicientheat'is generated by the contact of the raw sawdust with the stones tovaporize the moisture contained in the sawdust. the grinding stones todraw the ground sawdust and the vapor from the grinding mill, and thenthe reduced sawdust and the vapor are blown by the suction fans intocyclones or dust collectors, usually located on the roof of the lant Thev p s and he air Specification of Letters Patent.

Suction fans are installed adjacent Patented Feb. 14, 1922.

Application filed February 12, 1920. Serial No. 358,199.

drawn in by the suction fans pass out through the exhaust pipe on top ofthe cyclone, while the reduced and dry sawdust drops down into a pipewhich connects the bottom of the cyclone with a bolting machine havingscreens of bolting silk and similar to the bolts used in the manufactureof flour from cereals. By subjecting the sawdust to the bolting action,the coarse particles of the sawdust are separated from the wood flourand the latter is now conveyed to a hydraulic press and formed undervery heavy pressure into a bale having a burlap cover and weighingapproximately 350 lbs. The coarse sawdust separated from the wood flourduring the bolting operation is returned to the grinding mill to bereground into wood flour with the raw sawdust as above described.

It is understood that by vaporizing the moisture contained in the rawsawdust during the grinding action, the sawdust freed of the moisture isvery finely comminuted by the rinding stones to form wood flour of ahigi grade.

It will be noticed that by the arrangement described the sawdust iscompletely used up and formed into wood flour and the latter on accountof being deprived of its moisture is in condition for forming one of theconstituents of a composition of which phonograph records and otherarticles are'made.

It will further be noticed that it is very essential that metallicarticles are removed from the raw sawdust as otherwise the wood flour isimpure and the mill stones are liable to be injured by contact with themetallic substances.

It is understood that in the manufacture of wood flour as heretoforepracticed it has been customary to grind pieces of wood into flour, butthese pieces of wood had to be prepared especially for grinding, andhence the cost of the production of wood flour was considerable and verymuch higher than wood flour made from raw sawdust by the method abovedescribed. 1

From the foregoing it will be seen that by the process described,ordinary raw sawdust, which forms a practically valueless byproduct insaw mills, pulp mills and similar plants, is converted into a valuablewood flour and at comparatively little expense.

Having thus described my invention, I duced saw dust and vapors to ablast of air claim as new and desire to secure by Letters to force theminto an elevated separator to 10 Patent i separate the vapors from thereduced saw The herein described method of producing dust, anddelivering the saw dust to a b0lt- Wood flour, consisting in screeningraw saw ing cloth by gravity, whereby the saw dust dust, grinding thesaw dust under the deisthoroughlydried before being bolted so asvelopment of heat to vaporize the moisture to insure the pro er boltinof the same. contained in the saw dust, subjecting the re- 1 o JoiiN J.GIfNNINGHAM.

